TLDR: I stopped tesamorelin and my IGF-1 increased.
7/16/25: IGF-1 of 108
8/6/25: Started tesa @ 2mg/day
8/26/25: IGF-1 of 188; continued tesamorelin @ 2mg/day
12/8/25: stopped tesamorelin altogether due to up coming heart surgery and did not begin again.
1/16/26: IGF-1 of 202 (no other peps than stacked tirz and survo this entire time).
All labs are Labcorp.
I lost 38 lbs between Aug and Dec.
Not what I expected to see on 1/16/26.
Thoughts?
A few things could explain this, and it’s not as weird as it looks at first glance:
IGF-1 isn’t a direct “on/off” readout of tesamorelin. Tesa increases GH pulsatility, but IGF1 depends heavily on hepatic sensitivity, nutrition, insulin status, inflammation, and illness/stress.
Obesity = GH resistance. When you started tesa (Aug), you were still heavier and likely more GH resistant, so IGF1 didn’t rise much (188). After losing 38 lb, hepatic GH sensitivity can improve, allowing higher IGF1 even without tesa.
Severe caloric restriction can suppress IGF1, but once weight loss stabilizes and insulin sensitivity improves (especially on tirzepatide), IGF1 often rebounds.
Surgery/stress timing. You stopped tesa for upcoming heart surgery. Inflammatory stress and recovery can transiently suppress IGF1, followed by a rebound weeks later.
Assay variability is real. Lab's IGF-1 can vary 10–20% between draws depending on fasting status, time of day, recent illness, and binding protein dynamics.
GLP-1/GIP agonists don’t directly raise IGF1, but improved insulin signaling can indirectly increase hepatic IGF1 production.
For me....
This looks more like improved GH sensitivity after major weight loss, not a paradoxical effect of stopping tesamorelin. If IGF1 keeps climbing into supraphysiologic range without GH secretagogues, that’s when it’s worth monitoring more closely (trend > single value).
If this were me, I’d recheck in ~8–12 weeks under consistent conditions (fasted, morning, stable weight) before drawing conclusions.
